The country spends up to $90 million annually on weather-manipulation projects, and the Meteorological Law of the People’s Republic of China directs “governments at or above the county level” to “enhance their leadership over weather modification” and “carry out work in this field.” According to Yao Zhanyu, a weather-modification expert and professor at the Academy of Meteorological Sciences, climate control was first proposed by weather bureau chief Tu Changwang in 1956. Mao gave it his blessing: “Manmade rain is very important,” he commented. “I hope that meteorological professionals put more effort into it.” By the summer of 1958, the first rain-seeding flights took place in Jilin and Gansu provinces. This August—when the Olympics’ opening ceremonies take place—a more modest public celebration in Jilin province will honor 50 years of weather modification by the People’s Republic.

China’s meteorologists, though, weren’t the first to try cloud seeding. The General Electric Laboratory launched the first field experiments in 1946. The original principle established by the GE experiments was sound, and momentum for research grew so much that at one point in the ’70s, the United States spent $20 million annually on projects. Forty years ago, it was at least as plausible to trigger a downpour as to send a man to the moon, according to Hugh Willoughby, a meteorology professor at Florida International University who took part in major rain-making and hurricane-taming studies during the ’70s and early ’80s. But if American scientists want to pursue weather modification today, he says, “The burden of proof is really on them.” Presently the country spends only $500,000 on the science.

GE’s original starting point was that seeding can cause ice to form in cold clouds, or droplets to condense in warm ones. Yet cloud physics, it turns out, is considerably more complex than rocket science: The moon is an object of known size, moving predictably through space at a distance of about 240,000 miles. To put a man on the moon, he is put in a spaceship on a rocket and shot closer and closer to the target. A cloud seeder, by contrast, is never shooting at the same target twice. Not only is today’s cloud unlike yesterday’s, it is unlike the cloud it was five minutes ago. Its top is unlike its bottom, and the two may be changing places. Liquid water in it may be colder than neighboring ice. Rain falling inside it may never reach the ground.

Six decades after its enthusiastic beginnings, weather modification has been granted few successes by American scientists. In mountainous areas, seeding seems to be able to moderately increase snowfall in the winter. Insurance companies paid fewer hail-damage claims over the years in counties where private anti-hail contractors were at work. Recent studies also suggest that seeding clouds in the tropics with salt seems to produce more rain, though later and farther away than current theories can explain. According to a 2003 National Academy of Sciences Board of Atmospheric Sciences and Climate report, progress in weather modification “is not possible without a concerted and sustained effort at understanding basic processes in the atmosphere."

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Posted on Apr 17, 2008 at 7:57 AM
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